Tunnel dressing for use with negative pressure wound therapy system

ABSTRACT

A tunnel dressing for use in treating a tunneling wound using negative pressure wound therapy. The tunnel dressing includes an elongate permeable member having a closed distal end for entering the wound and an open proximal end into which an applicator is removably disposed for guiding the dressing into the wound. The tunnel dressing has a support structure adapted to transport wound exudates away from the wound and to resist compression under suction. The tunnel dressing also has a wound contact surface adapted to minimize tissue entanglement to facilitate removal. The support structure and wound contact surface may be formed from the same material or from two adjacent layers of different material.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of U.S. Provisional Application No.60/861,358 filed Nov. 28, 2006.

FIELD OF THE INVENTION

The present invention relates to the treatment of tunneling wounds usingsuction or negative pressure wound therapy. More particularly, thepresent invention relates to dressings for use in treating tunnelingwounds with suction.

BACKGROUND OF THE INVENTION

When treating wounds, occasionally wounds are encountered that are bestdescribed as “tunneling” wounds. A tunneling wound is substantiallytunnel-shaped, having an opening at the surface and extending into theflesh, forming a tunnel that is usually longer, and sometimessubstantially longer, than the width of the opening. Tunneling woundscan occur by themselves or in combination with a larger open wound,which may include one or more tunneling wounds. Because of their depth,tunneling wounds can present significant risks of infection and can beparticularly difficult to heal completely. Thus, it is desirable toprovide treatment that removes wound exudates (which can supportbacterial growth) and promotes healing of a tunneling wound, includingthe deepest portions of the wound. Poor healing in the deepest portionsof a wound can lead to abscesses if the shallower portion of the woundheals first and closes off the tunnel.

Suction or vacuum can be applied to a tunneling wound to promote wounddrainage and wound healing. A challenge in treating tunneling woundswith suction is that it can be difficult to place a dressing into a deeptunneling wound so that the dressing can effectively facilitate theremoval of wound exudates. Another challenge in treating tunnelingwounds with suction arises because the application of vacuum causesintimate contact between tissue and dressing materials, which can causethe tunnel dressing materials to stick to or become entangled with thewound surface. Entanglement or sticking of the dressing to the woundtissue creates a risk that pieces of the dressing can be broken off andleft in the wound when the dressing is removed, and because thetunneling wound is deep, these pieces are not detectable by theclinician removing the dressing. Entanglement or sticking of thedressing to the wound tissue can also cause considerable pain to apatient when the dressing is removed.

Accordingly, it would be desirable to provide a tunnel dressing that canbe placed in a tunneling wound so that vacuum can effectively reach thedeepest parts of the wound to remove wound exudates and to putbeneficial strain on the wound tissue. The dressing should be easy toinsert into a tunneling wound. Additionally, the dressing should beeasily removable from the tunneling wound without excessive entanglementor sticking to the wound tissue, and strong enough so that it can beremoved from the wound in one piece without breaking and leaving smallor large pieces in the wound. A tunnel dressing that allows vacuum toeffectively reach the deepest parts of the wound also enables fluids tobe removed from the deepest parts of the wound, which helps to avoidentrapment of fluid that can lead to an abscess.

Various dressings for use in tunneling wounds during suction therapyhave been devised in the prior art. Some dressings employ generallysolid rubber (e.g., silicone) or plastic devices having distinct holesor channels formed or cut into them for the purpose of transportingfluids. Other dressings employ a tube-like device having holes extendingthrough the tube walls. There are several disadvantages to these typesof devices. Because these devices are constructed from an impermeablematerial having discrete holes, vacuum cannot be applied uniformly andis thus concentrated on a relatively small portion of the wound surface.Further, the material from which these devices are formed is relativelyinflexible, making it difficult and uncomfortable for the patient whenthe devices are inserted into a wound. Still further, the presence ofdiscrete holes provides space into which large protrusions of tissue cangrow, which can cause considerable pain when the devices are removedfrom a wound.

Still other vacuum dressings employ foam having an open cell structurefor transporting fluids. When used for tunneling wounds, such dressingsare supplied as a rectangular piece of foam that must be cut by aclinician to match the estimated size of the tunneling wound. Adisadvantage of using foam is that foam lacks any significant tensilestrength and thus is prone to break when being extracted from the wound,leaving pieces behind within the tunneling wound cavity. Moreover, it isnot possible to readily discern when a piece of foam has broken off andremains lodged in the wound, because a torn or cut edge of the foamappears the same as a broken edge. The problem with foam is sosignificant and well known that after a clinician has cut a piece offoam to size, he or she is trained to tug on the foam piece to try toascertain if it is strong enough prior to insertion. A furtherdisadvantage of foam is that the foam lacks the stiffness required topush it into many tunneling wounds, so that a clinician often must use along Q-tip or other ad hoc device to help push the foam dressing intothe wound.

Yet other vacuum dressings utilize a tube interconnecting between asuction source at one end and a pad disposed at the opposite end, thetube otherwise having no holes or apertures to communicate vacuum to thewound. In use, the device is placed with the pad deep inside the woundand the tube partly disposed within the wound and extending out from thewound. Any unfilled space surrounding the tube within the wound may befilled with gauze. Numerous disadvantages result from this type ofarrangement. Often a tunneling wound is too narrow to allow the pad(with the connected tube) to be placed deep within the wound and tosubsequently completely surround the tube with gauze. Further, thedevice effectively applies vacuum forces only to the wound surface thatis in contact with the pad or is in contact with whatever gauze can bepacked in around the tube. Thus, the applied suction will generally beable to evacuate exudates from a wound but will be unable to applysuction forces to tissue that is in contact with only the tube. Stillfurther, when the pad is made from foam, all of the problems discussedabove with regard to foam dressings may result. In addition, the pad canbecome detached from the end of the tube and left in the wound when thedevice is withdrawn. Also, there is no mechanism for introducing thedevice into a deep tunnel wound other than by pushing on the flexibletube.

SUMMARY OF THE INVENTION

A tunnel dressing is provided for use in treating a tunneling wound withsuction, the tunnel dressing comprising an elongate permeable memberhaving a distal end adapted for entering the wound and an opposedproximal end. The permeable member further has an outer surface and acavity opening onto the outer surface. An applicator can further beprovided having a distal portion disposed within the cavity and aproximal portion extending out of the permeable member, the applicatorbeing adapted to guide the dressing into the wound. The cavity can openonto the outer surface at the proximal end of the permeable member, orthe cavity can open onto the outer surface at a location between thedistal end and the proximal end of the permeable member.

A tunnel dressing is provided for use in treating a tunneling wound withsuction comprising an elongate permeable member having a closed distalend adapted for entering the wound, an opposed proximal end, an outerwound contact surface, and an elongate cavity opening onto the proximalend and extending into the permeable member toward the distal end. Thecavity is adapted to receive an applicator for guiding the dressing intothe wound. The tunnel dressing can further comprise an applicator havinga distal portion adapted to be removably received in the cavity and aproximal portion extending outwardly from the permeable member.

A tunnel dressing is provided for use in a treating a tunneling woundwith suction comprising an elongate permeable member having a closeddistal end adapted for entering the wound, an opposed closed proximalend, an outer wound contact surface, and a cavity opening onto the woundcontact surface at a location between the distal end and the proximalend. The cavity is adapted to receive an applicator for guiding thedressing into the wound. The tunnel dressing can further comprise anapplicator having a distal portion adapted to be removably received inthe cavity and a proximal portion extending outwardly from the permeablemember.

A tunnel dressing is provided for use in treating a tunneling wound withsuction comprising an elongate member. The elongate member comprises aclosed distal end, an opposed proximal end, an elongate cavity openingonto the proximal end, a permeable inner layer surrounding the cavity,the inner layer being adapted for transport of wound exudates, and apermeable outer layer enveloping the inner layer. The outer layer has awound contact surface. The tunnel dressing can further comprise anelongate applicator removably disposed within the cavity for guiding thedressing into the wound.

A method is provided for treating a tunneling wound with suction. Themethod comprises providing a tunnel dressing comprising an elongatepermeable member having a closed distal end adapted for entering thewound and an opposed proximal end, the permeable member further havingan outer surface and a cavity opening onto the outer surface, the tunneldressing further comprising an applicator having a distal portiondisposed within the cavity and a proximal portion extending out of thepermeable member, the applicator being adapted to guide the dressinginto the wound; inserting the tunnel dressing into the tunneling woundby grasping the proximal portion of the applicator and applying gentleforce to push the distal end of the dressing into the wound untilincreased resistance is detected; placing a wound cover over the tunneldressing and adhering the wound cover to skin surrounding the wound toform a substantially air-tight seal, the wound cover being adapted tocommunicate suction via a conduit from a suction source to the wound;and applying suction from the suction source to the wound.

A system for treating a tunneling wound with suction is provided. Thesystem comprises a tunnel dressing comprising an elongate permeablemember having a distal end adapted for entering the wound and an opposedproximal end, the permeable member further having an outer surface and acavity opening onto the outer surface; and an applicator having a distalportion disposed within the cavity and a proximal portion extending outof the permeable member, the applicator being adapted to guide thedressing into the wound; a suction source; a wound cover adapted to forma substantially air-tight seal over the wound dressing by adhering toskin surrounding the wound; and a conduit having an end operativelyassociated with the wound cover and an opposite end operativelyassociated with the suction pump, to communicate suction to the wound.

A method of making a tunnel dressing for use in treating a tunnelingwound with suction is provided, comprising forming a stack comprisingtwo layers of a first fibrous material sheet sandwiched between twolayers of a second fibrous material sheet, the sheets having edges;ultrasonically welding the four layers together to form a unitary piece;trimming excess material away from the unitary piece between the weldand the edges of the sheets to form an article having three sealed edgesand an un-sealed edge; and inverting the article to form the tunneldressing having an internal weld.

A tunnel dressing for treating a wound with suction comprising agenerally elongate permeable member is provided. The permeable membercomprises a distal end; a proximal end; a cohesive permeable outer woundcontact surface; and a permeable internal core. The wound contactsurface is adapted to transport wound exudates from the wound tissue tothe internal core and is generally free of protrusions that could becomeembedded in the wound tissue and left behind in the wound tissue whenthe tunnel dressing is removed. The core has interconnecting intersticesextending from the distal end to the proximal end for transporting woundexudates along the elongate member, at least some of the intersticesbeing resistant to complete collapse under the compressive forces oftherapeutic suction and in the presence of wound exudates such the coreremains capable of transporting fluid. The tunnel dressing hassufficient tensile strength to resist breakage during removal from thewound after exposure to therapeutic suction and wound exudates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tunnel dressing.

FIG. 2 is a cross-sectional view of an embodiment of the tunnel dressingof FIG. 1 taken through section 2-2.

FIG. 3A is a cross-sectional view of an exemplary open wound having atunneling wound portion into which a tunnel dressing would be inserted.

FIG. 3B is a cross-sectional view of an exemplary tunneling wound intowhich a tunnel dressing would be inserted.

FIG. 4 is a cross-sectional view showing a tunnel dressing as in FIG. 1inserted into a tunneling wound as in FIG. 3B.

FIG. 5 is a cross-sectional view of an embodiment of the tunnel dressingof FIG. 1 taken through section 2-2.

FIG. 6 is a partial perspective cross-sectional view of the tunneldressing of FIG. 5.

FIG. 7A is a cross-sectional view showing a tunnel dressing as in FIG. 1inserted into a tunneling wound as in FIG. 3A, wherein suction isapplied to the wound.

FIG. 7B is a cross-sectional view showing a tunnel dressing as in FIG. 1inserted into a tunneling wound as in FIG. 3B, wherein suction isapplied to the wound.

FIG. 8 is a perspective view of a tunnel dressing.

FIG. 9 is a perspective view of a tunnel dressing.

FIG. 10 is a perspective view illustrating a method of making a tunneldressing.

DESCRIPTION OF THE INVENTION

Referring to the drawings, where like numerals identify like elements,there is shown in FIGS. 1 and 2 a tunnel dressing 10 for treating atunneling wound with suction according to an embodiment of theinvention. The tunnel dressing 10 has a generally elongate shape toprovide for insertion of the tunnel dressing 10 into a tunneling wound,such as shown in FIGS. 3A and 3B. The tunnel dressing 10 preferably hasa closed distal end 46 and an open proximal end 48, and sides 47spanning between the ends 46, 48, such that the closed end 46 can beinserted into a tunneling wound with the open end 48 protrudingoutwardly from the wound. The tunnel dressing 10 can have a generallyround or circular cross-section, as shown in FIG. 1, or can have a moreoblong or ovalized cross-section, depending on the shape of thetunneling wound into which the tunnel dressing 10 will be inserted. Thetunnel dressing 10 can be used, as illustrated for example in FIGS. 7Aand 7B, for treating a tunneling wound with suction as part of anegative pressure wound therapy system 70.

The tunnel dressing 10 comprises an outer sheath layer 12 contacting aninner core or support layer 14 along at least a portion of an interface22. The tunnel dressing 10 has a distal end 46 and a proximal end 48.The sheath 12 and the layer 14 can be bonded to each other along theirrespective edges or across a portion of, or all of, the interface 22.Alternatively, the sheath layer 12 can be slipped over the support layer14 as a cover and need not be attached thereto. The outer sheath 12 hasa wound contact surface 20 and the inner layer 14 has an inner surface24. The outer sheath 12 is thin relative to the inner layer 14, theinner layer 14 provides structural support to the tunnel dressing 10 andthe outer sheath 12 providing a suitable wound contact surface 20. In anembodiment, the support layer 14 is about 0.080 inches thick and thesheath 12 is about 0.003 inches thick.

The outer sheath 12 readily transports fluid therethrough from the woundto the support layer 14 and preferably has sufficient structuralintegrity so as to not leave fibers behind in the wound. The woundcontact surface 20 is cohesive and is sufficiently smooth to allow foreasy insertion and removal by minimizing the adherence of new tissuethereto. The inner layer 14 provides structural support to the sheath 12and comprises a permeable fibrous structure to allow for transport ofexudates lengthwise along the dressing 10 (i.e., in the direction fromthe distal end 46 to the proximal end 48) and out of the wound whensuction is applied by a negative pressure wound therapy system 70.Because the inner layer 14 may include fibers that are only looselycoupled together, the outer sheath 12 serves to retain loose fibers sothey are not left in the wound when the dressing 10 is removed.

The sheath 12 is made from a permeable material adapted to allow woundexudates to be transported therethrough, such that when the wound issubjected to suction, wound exudates can be drawn away from the woundsurface. Under suction, exudates are drawn through the sheath 12 andinto the layer 14, and then through the layer 14 towards the proximalend 48 of the tunnel dressing 10. The sheath 12 is preferably made froma fibrous material having a high structural integrity, such as nonwovenpolyester, with tightly coupled fibers that are not prone to shed intothe wound. The wound contact surface 20 of the sheath 12 has arelatively smooth structure as can be achieved by calendaring thematerial of the sheath 12. The fibers of the sheath 12 are preferablylong continuous fibers that can be bonded together with heat.

The contact surface 20 is substantially without very large voids ordiscontinuities (i.e., voids greater than an order of magnitude largerthan the average interstitial space between adjacent fibers), in orderto minimize the tendency for large protrusions of wound tissue to becomeentangled in the tunnel dressing 10. Rather, the contact surface 20comprises a large number of small openings or interstitial spacesbetween fibers which enables good fluid transport. The smallinterstitial spaces between fibers in the contact surface 20 alsominimize tissue entanglement and prevent any loose fibers from the layer14 from becoming embedded in the wound tissue and left behind in thewound. Further, the fibers of the sheath 12 generally do not protrude orterminate beyond the wound contact surface 20, thus minimize thepossibility that fibers can be embedded in wound tissue or left behindin wound tissue when the dressing 10 is removed after the application ofsuction therapy.

The permeable nature of such a fibrous material of the sheath 12 allowsfor application of vacuum to more of the wound surface than can beobtained with dressings having discrete holes or channels. The polyesterfibers generally do not absorb fluids, meaning that they do not swellwhen subjected to moisture but instead allow liquid to be conductedalong their surface and through the fibrous material under the force ofapplied suction. One such material is sold by Ahlstrom Corp. as Hollytex3257, a spunbond polyester sheet having a highly calendared surface.Other such materials having slightly larger interstitial spaces areHollytex 3256 and Hollytex 3249. Other similar or equivalent materialscan be used. The sheath 12 is preferably made from a sheet of material,the sheet being formed by heat sealing or welding into a sheath-likeshape with a closed end onto the support layer 14, as shown in FIGS. 1and 2. The heat sealing or welding process provides additional strengthto the sheath 12, and thus to the dressing 10, which eliminates orsubstantially reduces the risk that a portion of the tunnel dressing 10can break off and be left in a tunneling wound.

The core or support layer 14 is made from a permeable material having astructure that imparts compression resistance to enable the layer 14,and thus the tunnel dressing 10, to resist collapse or compression underthe force of therapeutic suction, such as that applied during negativepressure wound therapy. A negative pressure wound therapy system canapply negative pressures to a wound in the range of about 5 mm Hg toabout 500 mm Hg, preferably in the range of about 25 mm Hg to about 200mm Hg, and most preferably in the range of about 30 mm Hg to about 75 mmHg.

The layer 14 is also adapted to transport wound exudates that are drawnfrom the wound through the sheath 12 into the layer 14, so that theexudates can be removed from the dressing 10 by suction applied at theend 48 of the dressing 10 by a negative pressure wound therapy system70. The layer 14 is preferably made from a fibrous material such asnonwoven polyester felt. During the felting process, fibers becomeoriented in multiple directions, which improves the compressionresistance of the layer 14. The fibrous material of the layer 14preferably has interconnected interstices throughout, at least some ofthe interstices resisting complete collapse under the compressive forcesresulting from negative pressure wound therapy and in the presence ofwound exudates so that the interstices remain capable of transportingfluid through the dressing. As with the fibers used to form the sheath12, the polyester fibers of the support layer 14 generally do not absorbfluids, meaning that they do not swell when subjected to moisture butinstead allow liquid to be conducted along their surface and through thefibrous material under the force of applied suction. One such materialis felt made from polyester fibers, the material having a thickness ofabout 0.080 inches and a basis weight of 5 ounces per square yard.

In an embodiment, the tunnel dressing 10 is about 6 inches long andabout 0.25 inches in diameter (i.e., a length to diameter ratio of about24), although the dressing 10 can be made in a wide range of lengths,diameters, and length/diameter combinations. The fluid transportproperties of the support layer 14 enable the withdrawal of exudates bysuction from very deep wounds. The layer 14 is preferably made from asheet of material, the sheet being formed by heat sealing into asheath-like shape with a closed end as shown in FIGS. 1 and 2 such thatthe inner surface 24 of the layer 14 faces itself and forms a cavity 18within the dressing 10.

The dressing 10 comprising the support layer 14 and the sheath 12 can bemade from layered sheets of material, as depicted in FIG. 10. Two sheets412 a and 412 b of material for forming the sheath 12 (e.g., spunbondpolyester) are sandwiched between two sheets 414 a and 414 b of materialfor forming the support layer 14 (e.g., polyester felt) to form a stack490 of layered materials. Next, the four layers are preferablyultrasonically welded together along a generally U-shaped weld 480forming essentially three sides of a rectangle, leaving a non-weldedportion forming essentially a fourth side of the rectangle. The cornersof the rectangle can be more rounded or less rounded depending on thedesired configuration of the dressing 10.

It is contemplated that the four layers could be formed by layering asheet of material 412 on top of a sheet of material 414 and folding thetwo layers over on themselves along a fold line, so that the stack onlyneed be welded along a generally L-shaped weld line forming two sides ofa rectangle, the third closed side being formed by the fold line. It isfurther contemplated that the stack could be welded along a generallybox-shaped weld line forming essentially all four sides of a rectangle.Then, the weld along a portion forming essentially one side of therectangle can be cut off to create a non-welded opening. Alternatively,all four welds can be left in place and an opening can be cut throughone of the layers 414 a and one of the layers 412 a to enable access toa cavity formed between the layers 412 a and 412 b.

Next, the layers of material 414 a, 412 a, 412 b, and 414 b are cutaround the weld 480 to remove the excess material between the weld 480and the edges of the stack 490, as well as any excess material betweenthe end of a U-shaped or L-shaped weld 480 and the edges of the stack490 at the non-welded opening. The remaining article has two layers ofsupport material 414 a and 414 b on the outside surrounding two layersof sheath material 412 a and 414 b, a weld 480 on essentially two orthree edges of the article that is relatively hard and jagged comparedwith the layers of material, and an opening at one end of the articlewhere the layers are not welded together. Finally, the article isinverted or turned inside out to form a tunnel dressing 10 having aninternal weld 480, an outer sheath 12 of spunbonded material, an innercore or support layer 14 of felt, and a cavity 18 disposed within theinner support layer 14 (i.e., between the sheets 414 a and 414 b).Cavities also exist between each of the sheets 414 a/414 b and itscorresponding adjacent sheet 412 a/412 b.

The resultant tunnel dressing 10 has a closed distal end 446 and an openproximal end 448, with the weld 480 extending internally along thelength of the dressing from the closed end 446 to the open end 448. Theweld 480 imparts additional tensile strength to the dressing so thatafter the application of suction to a wound having the dressing 10therein, the dressing 10 can be removed without breaking and withoutleaving any remnants of the dressing 10 in the wound cavity. The weld480 also extends internally along the distal closed end 446 of thedressing 10, imparting additional strength to the closed end 446 toinhibit, or to assist in preventing, the applicator rod 16 from pushingthrough the closed end 446 when the dressing 10 is being inserted into awound.

The tunnel dressing 10 is preferably inserted into a tunneling woundusing a semi-flexible applicator rod 16 removably disposed within thecavity 18. Exemplary wounds are illustrated in FIGS. 3A and 3B. Theapplicator rod 16 is preferably made from a relatively thin piece ofmaterial that is sufficiently rigid to transmit force along its lengthas required to gently push and guide the dressing 10 into the wound, yetis sufficiently flexible to follow the contours of the tunneling woundas the dressing 10 is being inserted. The rod 16 is preferably lessflexible than the dressing 10. The rod 16 can comprise plastic, wood,metal, paper, and/or other suitable material.

The rod 16 engages the far end of the tunnel dressing 10 so that when aclinician pushes on the rod 16, force is transmitted to the distal end46 of the tunnel dressing 10, the end 46 thereby pulling the remainderof the tunnel dressing 10 into the tunneling wound. In a tunneling wound62 such as shown in FIGS. 3B and 7B, the tunnel dressing 10 can be usedalone to dress the wound cavity for treatment of the wound 62 withsuction. In an open wound 50 including a tunneling portion 52 such asshown in FIGS. 3A and 7A, the tunnel dressing 10 can be used incombination with a wound packing 80 such that the tunnel dressing 10dresses the tunneling portion 52 and the wound packing 80 dresses theremainder of the wound cavity 50 for treatment of the wound 50 withsuction. Many wound packings 80 are known in the art, including packingsdisclosed in U.S. patent application Ser. No. 10/981,119, filed on Nov.4, 2004 and commonly assigned with the present application.

Providing the tunnel dressing 10 in a sheath-like shape having a closeddistal end 46 is advantageous compared with attempting to push a flatsheet into a tunneling wound using a rod. In particular, the dressing 10can easily be guided into a deep tunneling wound with only a smallamount of force, the smooth material of the contact surface 20 on thetip 46, in conjunction with the contact surface 20 on the sides 47,guiding the dressing 10 as the rod 16 is gently pushed inwardly into thewound. Thus, pain is minimized and the dressing 10 can be placed as faras desired into the wound.

For clarity of description, the process of inserting the tunnel dressing10 is generally described herein with reference to a tunneling wound 60as illustrated in FIGS. 3B, 4, and 7B, it being understood that thedescription applies similarly to an open wound 50 having a tunnelingportion 52 as illustrated in FIGS. 3A and 7A. A tunneling wound 62 in atissue surface 68 can be defined by walls 66 and a bottom end 64.Alternatively, a tunneling wound can be defined as a wound 50 in atissue surface 58 having a tunneling portion 52 defined by walls 56 anda bottom end 54.

To insert the tunnel dressing 10 into a tunneling wound 62, a cliniciangrasps the rod 16 at a proximal end 17 protruding from the open end 48of the dressing 10. A dressing 10 should be selected that is somewhatlonger than the anticipated depth of the wound 62 so that a portion ofthe dressing 10 remains protruding from the wound 62 after insertion.The protruding portion of the dressing 10 can be readily grasped forremoval. The clinician gently guides the tunnel dressing 10 into thetunneling wound 62 by applying light force along the length of the rod16. The rod 16, the sheath 12, and the layer 14 are sufficientlyflexible to follow the countours of the walls 66 of the tunneling wound62 as the dressing 10 is inserted thereinto. When the clinician feelsincreased resistance indicating that the dressing 10 is reaching the end64 of the wound 62, the clinician can gently withdraw the rod 16,leaving the dressing 10 in place within the wound 62.

Withdrawal of the rod 16 leaves a small elongate cavity 18 within thedressing 10 extending from the open end 48 to near the closed end 46.The cavity 18 serves a functional purpose during use of the dressing 10,in addition to providing a receptacle for the applicator rod 16 duringinsertion of the dressing 10. The cavity 18 has less resistance tocollapse than the permeable material of the support layer 14 or of thesheath 12, and therefore enables the tunnel dressing 10 to be compactedsomewhat in width as the wound cavity 62 is drawn together under appliedsuction without hampering the fluid transport capacity of the layer 14or the sheath 12 of the dressing 10.

In order to encourage tissue growth in the end 64 of the wound 62 whensuction is applied to the dressing 10, the clinician preferablypartially withdraws the dressing 10 slightly away from the wound end 64before suction is applied by grasping a portion of the dressingprotruding from the wound 62 and pulling gently outwardly. The preferredposition of the tunnel dressing 10 within the wound 62 is shownschematically in FIG. 4, the dressing 10 being fully inserted into thewound 62 and then partially withdrawn slightly to leave a space 90 fortissue growth in the wound end 64. The space 90 is preferably about 1centimeter from the wound end 64 to the dressing 10, recognizing that alarger or smaller space may be desired depending on the depth, width,exudate rate, and other characteristics of the wound 62. Once thedressing 10 is in place, if a larger portion of the dressing 10 isprotruding from the wound 62 than desired or than needed for laterremoval of the dressing 10, the excess dressing 10 may be cut off topreferably leave a small protruding portion.

After the tunnel dressing 10 has been installed into the wound 62, aconventional vacuum or negative pressure wound therapy system can beused to apply suction to the wound. Such a negative pressure woundtherapy system 70 is shown generally in FIGS. 7A and 7B, the systemcomprising a suction source 78, a wound cover 72 having an adhesivecoating 74 on one side for adhering to skin surrounding a wound, and aconduit 76. The conduit 76 has an end operatively associated with thewound cover 72 and an opposite end operatively associated with thesuction source 78 for communicating suction from the suction source 78to the wound 62 beneath the wound cover 72. Non-exhaustive examples ofapplicable vacuum or negative pressure wound therapy systems aredescribed in detail, for example, in U.S. patent application Ser. No.11/786,475, filed on Apr. 12, 2007 and in U.S. patent application Ser.No. 11/181,128, filed on Jul. 14, 2005, both commonly assigned with thepresent application. The suction source 78 can comprise a stationarysuction system such as those commonly found in hospitals, or a portablepump or bellows or other equivalent mechanism for providing anddelivering a therapeutic level of suction to the wound.

For a tunneling wound 62 of the type shown in FIG. 3B, a wound cover 72can be placed directly over the tunnel dressing 10, as shown in FIG. 7B.The cover 72 comprises a semi-permeable material that is generallyair-tight but allows vapor and/or moisture to be transportedtherethrough. The cover 72 is adhered to the skin 68 surrounding thewound by the adhesive coating 74 to provide a substantially air-tightseal over the wound. For a wound 50 of the type shown in FIG. 3A, thewound 50 having a tunneling portion 52, a packing 80 is preferably usedto fill the open cavity of the wound 50 before applying the cover 72 byadhering the adhesive layer 74 to the skin 58 surrounding the wound 50.

When suction is applied by the negative pressure wound therapy system 70to a wound 62 having the tunnel dressing 10 inserted thereinto, thesuction is transmitted through the permeable material of the layer 14and the sheath 12 to the wound tissue along the sides 66 and end 64 ofthe wound 62. The wound tissue is drawn against the wound contactsurface 20, causing compression force on the dressing 10. In absorbingthe compression force, the cavity 18 collapses inwardly, allowing atleast a portion of the interstitial spaces within the support layer 14and sheath 12 to remain open so that the suction can draw wound exudatesout of the wound 62 through the wound cover 72 and into the conduit 76.Once the cavity 18 has collapsed, the support layer 14 can still besubjected to compressive forces due to the applied suction. The supportlayer is capable of resisting compression to maintain its fluidtransport properties.

Preferably, the support layer 14 retains at least 10% of its originaluncompressed volume when subjected to a suction of 75 mm Hg. In anembodiment, prior to the application of suction, the support layer 14comprises about 5% polyester fibers and about 95% void space. In anembodiment, after application of a suction of 75 mm Hg, the supportlayer 14 retains about 75% of its original volume (so that thecompressed layer 14, by volume, is about 7% fibers and 93% void space).To maintain adequate ability to transport wound exudates and providesuction to the wound tissue, the support layer preferably maintains atleast about an equal amount of void space to the amount of fiber space,or about 10% of its original uncompressed volume (so that the compressedlayer 14, by volume, is about 50% fibers and 50% void space).

Depending on the negative pressure wound therapy regimen, suction can beapplied continuously or intermittently for periods ranging from a fewhours to several days. When the time comes to remove or change thetunnel dressing 10, the clinician first removes the wound cover 72 andany packing 80 that may have been used. Then, grasping the portion ofthe dressing 10 protruding from the wound 62, the clinician gently pullsthe dressing 10 to extract it from the tunnel wound 62. The structure ofthe dressing 10 is sufficiently strong that it retains its tensilestrength even after being subjected to wound exudates and suction, suchthat the dressing does not tear or come apart as it is being removed. Asdiscussed above with regard to FIG. 10 and a method of making thedressing 400, a weld 480 is formed extending along the inside of thedressing 400 from the distal end 446 to the proximal end 448. Similarly,in the tunnel dressing 10 as shown in FIGS. 1, 2, 4, 7A, and 7B, a weld(not shown) extends along the inside of the dressing 10 from the distalend 46 to the proximal end 48, the weld providing additional tensilestrength to the dressing 10 to prevent tearing or breaking apart of thedressing 10 upon removal from the wound 62.

The tunnel dressing 10 can further be provided with regularly spacedmarkings 42 along the length of the sides 47 (i.e., from near the closeddistal end 46 to near the open proximal end 48), as shown in FIG. 1. Themarkings 42 provide a visual indication of how deep the wound is, andcan be used to determine the progress of a wound as it heals. Themarkings 42 also provide a measure to indicate how far the dressing 10is partially withdrawn after it has been fully inserted, to leavesufficient space 90 for tissue growth in the wound end 64. The markings42 can be made using a biocompatible ink, a series of slight depressionsor protrusions from the surface 20 of the dressing 10, or other similarregularly repeated visual indicator.

The tunnel dressing 10 can also be provided with a visual marking 44 atthe tip of the closed end 46, to provide assurance that the entiredressing 10 has been withdrawn. If a clinician withdraws the dressing 10and the visual marking 44 is not present, the clinician is alerted thata part of the dressing 10 may remain within the wound cavity. Themarking 44 is preferably made using a biocompatible ink, an embossing,or other similar identifiable visual indicator.

The support layer 14 of the tunnel dressing 10 can include structuralfeatures to enable the dressing 10 to resist compression when subjectedto vacuum. Resisting compression enables good transport of woundexudates away from the wound surface 66 and out of the tunnel wound 62.In an embodiment, the layer 14 comprises randomly disposed fibers. Inanother embodiment, as shown in cross-section in FIG. 5, a support layer30 comprises multiple structured voids or cavities 32 opening onto theinner surface 24 and extending into the layer 30. The structured voids32 provide structural support to enable the layer 30 to resistcompression under vacuum to both maintain the surface 20 of the dressing10 in contact with the wound surface 66 and to keep open at least aportion of the interstitial spaces within the fibrous material of thelayer 30 to provide for good fluid transport.

Each void 32 comprises a cavity opening onto the inner surface 24 andextending a depth into the layer 30. The voids 32 may extend through theentire thickness of the layer 30, or may extending only to a depth thatis less than the thickness of the layer 30. Each void 32 comprisessidewalls 34 extending generally perpendicularly to the surface 24, acap 36 bridging the sidewalls to form a cavity within the void 32, andan opening 38 on the surface 24. The voids 32 are spaced apart in thematerial so that the openings 38 are correspondingly spaced apart on thesurface 24. The width of the openings 38 in the surface 24 is preferablygreater than about 0.1 mm and less than about 10 mm, more preferablybetween about 0.5 mm and about 5 mm, and most preferably about 2 mm. Thedepth of the voids 32, measured from the opening 38 in the surface 24 tothe cap 36, is preferably greater than about 0.1 mm when suction isapplied, more preferably between about 0.2 mm and 5 mm, and mostpreferably about 1.5 mm. The voids 32 are preferably dimple voids 32that are generally circular in shape, as shown in FIG. 6, but can alsobe oblong, oval, square, triangular, channels, or other geometric shapecapable of providing structural rigidity. The voids 32 can be formedinto the layer 30 by several methods, including by heat stamping orvacuum forming, by applying molten material directly to a mold as inmeltblowing, or by mixing fibers with an adhesive and spraying the mixonto a textured surface.

FIG. 8 shows another embodiment of a tunnel dressing 210 for treating awound with suction. The tunnel dressing 210 is made from a permeablematerial 212 preferably having a fibrous structure similar to thesupport layer 14 in the tunnel dressing 10 of FIG. 1. The tunneldressing 210 has a closed proximal end 248 and a closed distal end 246spanned by at least a sidewall 247. The distal end 246 is adapted toenter a wound, so that when the dressing 210 is inserted into atunneling wound, the distal end 246 is inserted first and leads the wayinto the depths of the wound. The tunnel dressing 210 further has aninternal cavity 218 and a wound contact surface 220. The internal cavity218 opens onto the wound contact surface 220 at an opening 250 disposedin the sidewall 247 between the proximal end 248 and the distal end 246.The cavity 218 extends at least from the opening 250 to near the distalend 246. The internal cavity 218 may also extend from the opening 250toward the proximal end 248. An applicator rod 216 having a proximalportion 217 and a distal portion (not shown) can be used to guide thedressing 210 into a wound, the distal portion being removably disposedwithin the cavity 218 and the proximal portion 217 extending out fromthe tunnel dressing 210. After the dressing 210 is inserted into thewound, the rod 216 can be removed without disturbing the dressing 210 inthe wound.

When the dressing 210 is formed from a fibrous material 212 such aspolyester felt, the material 212 can be thermally seared along the outerwound contact surface 220 to minimize fiber shedding. Alternatively, thedressing 210 can be formed from a fibrous material 212 comprising acombination of polyester fibers and biocomponent fibers. Bicomponentfibers are fibers that have a core of one material and a sheath of aslightly different material. The material of the sheath preferably has alower melting temperature than the material of the core so that productsmade from such fibers can be heated to a temperature that melts thesheath but not the core. The molten sheath material then locks or fusesthe fibers together when cooled so that there is less shedding offibers. In an embodiment, the dressing 210 could be formed from 85%standard polyester fiber and 15% bicomponent fibers having a polyestercore with a 250° C. melting temperature and a copolyester sheath with amelting point ranging between about 110° C. and about 220° C. After itis formed into the desired shape, the material 212 of the dressing 210could then be heated so that the sheath material melts to create acontact surface 220 less likely to shed fibers into the wound.

FIG. 9 shows another embodiment of a tunnel dressing 310 for treating awound with suction. The tunnel dressing 310 is made from a permeablematerial 312 preferably having a fibrous structure similar to thesupport layer 14 in the tunnel dressing 10 of FIG. 1. The tunneldressing 310 has an open proximal end 348 and a closed distal end 346adapted to enter a wound, so that the when the dressing 310 is insertedinto a tunneling wound, the distal end 346 is inserted first and leadsthe way into the depths of the wound. The tunnel dressing 310 furtherincludes an internal cavity 318 and a wound contact surface 320. Theinternal cavity 318 opens onto the proximal end 348 of the dressing 310and extends within the dressing 310 to near the distal end 346. Anapplicator rod 16 having a proximal portion 17 and a distal portion (notshown) can be used to guide the dressing 310 into a wound, the distalportion being removably disposed within the cavity 318 and the proximalportion 17 extending out from the tunnel dressing 310. After thedressing 310 is inserted into the wound, the rod 16 can be removedwithout disturbing the dressing 310 in the wound. The wound contactsurface 320 of the dressing 310 can be prepared in any of the mannerspreviously discussed with regard to the wound contact surface 220 of thedressing 210 shown in FIG. 8.

While the invention has been disclosed with reference to certainpreferred embodiments, numerous modifications, alterations, and changesto the described embodiments are possible without departing from thesphere and scope of the invention, as defined in the appended claims andequivalents thereof. Accordingly, it is intended that the invention notbe limited to the described embodiments, but that it have the full scopedefined by the language of the following claims.

1. A tunnel dressing for treating a wound with suction comprising agenerally elongate permeable member comprising: a distal end; a proximalend; a cohesive permeable outer wound contact surface; and a permeableinternal core; the wound contact surface being adapted to transportwound exudates from the wound tissue to the internal core, the woundcontact surface being generally free of protrusions that could becomeembedded in the wound tissue; the core having interconnectinginterstices extending from the distal end to the proximal end fortransporting wound exudates along the elongate member, at least some ofthe interstices being resistant to complete collapse under thecompressive forces of therapeutic suction and in the presence of woundexudates such the core remains capable of transporting fluid; the tunneldressing having sufficient tensile strength to resist breakage duringremoval from the wound after exposure to therapeutic suction and woundexudates.
 2. The tunnel dressing of claim 1, wherein the internal corehas a structure adapted to maintain at least 75% of its original volumewhen subjected to a suction of 75 mm Hg.
 3. The tunnel dressing of claim2, wherein the structure is adapted to maintain at least 10% of itsoriginal volume when subjected to a suction of 75 mm Hg.
 4. The tunneldressing of claim 1, wherein the internal core comprises a fibrousmaterial.
 5. The tunnel dressing of claim 4, wherein the outer woundcontact surface is formed by thermally searing the fibrous material. 6.The tunnel dressing of claim 1, wherein the outer wound contact surfacelayer comprises a calendared fibrous material.
 7. The tunnel dressing ofclaim 1, wherein the outer wound contact surface is thin relative to theinternal core.
 8. A tunnel dressing for use in treating a tunnelingwound with suction comprising an elongate member comprising: a closeddistal end; an opposed proximal end; an elongate cavity opening onto theproximal end; a permeable inner layer surrounding the cavity, the innerlayer being adapted for transport of wound exudates, wherein thepermeable inner layer comprises a fibrous material; and a permeableouter layer enveloping the inner layer, the outer layer having a woundcontact surface.